Invalidate cache when performing additional post operations

[pupi1985]

There are a few situations that were being missed when invalidating question caches:

• Creating answers
• Creating comments
• Updating content of question
• Updating content of answer
• Updating content of comment

Having these cache invalidations set would allow users to configure longer cache periods.

[svivian]

Thanks for this. My original thought was to balance cache hits with too many cache invalidations, but I think you're right this allows longer cache periods (and therefore more time saved overall).